Chronic pain associated with conditions such as muscle spasms, tendonitis and sciatica is not only very painful to the individual, but is usually very difficult to treat. Inadequate treatment of chronic pain can be debilitating to humans.
Muscle spasms are violent, involuntary contractions of a muscle or a group of muscles. They affect a large segment of the population and are often very painful. The pain resulting from muscle spasms often is chronic, i.e. lasts for one day or even longer. By contrast, the pain associated with leg cramps, which usually radiates from the calf, and can last from a few seconds up to ten minutes. See for example, Weiner et al., JAMA 244:2332-2333 (1980).
Conditions involving muscle spasms may result from injury or trauma to the affected muscle or nerve that innervates that muscle. Some conditions involving muscle spasms include lower back and cervical spine syndromes and whiplash injuries.
Other painful conditions include sciatica and tendonitis. Sciatica is a condition characterized by pain radiating from the muscles in the back into the buttocks. Sciatica may result from trauma to the spinal cord or to the sciatic nerve. Another condition characterized by chronic pain is tendonitis, which is an inflammation of tendons and of tendon-muscle attachments.
The debilitating effects of chronic pain are not only a source of anxiety and distress for the individual, but represent a tremendous cost to society. For example, workers suffering from chronic pain are frequently absent from work for weeks or even longer. This poses a great expense to the employer in sick-time coverage, disability pay and to society in lost productivity.
At present, a variety of medicinals are used in an attempt to relieve or correct these conditions associated with chronic pain. These medicinals include muscle relaxants such as methocarbamol, carisoprodol and mephenesin. Nonsteroidal anti-inflammatory agents such as ibuprofen, aspirin, and indomethacin are also used in conjunction with muscle relaxants for treating muscle spasms, tendonitis and sciatica. However, these medicinals provide, at most, partial relief and do not provide relief considered adequate by most people.
Niacin, which is also known as Vitamin B.sub.3, is an important biochemical component that acts as a catalyst for cellular reactions and synthesis of important coenzymes such as nicotine adenosine dinucleotide and nicotine adenosine dinucleotide phosphate. These coenzymes play a key role in glycolysis, fatty acid synthesis and in deamination of amino acids.
Niacin is one of the oldest pharmacologic agents used in the treatment of hyperlipidemia. At doses of 3-6 g/day, it is highly effective in reducing elevated levels of plasma cholesterol and triglycerides. Niacin is known to inhibit adipose tissue lipolysis, reduce plasma free fatty acid levels and decreases very low density lipoprotein. This has been shown to be a benefit in preventing nonfatal myocardial infarction due to arteriosclerotic heart disease.
Large doses of niacin (1-6 g/day) have also been used as adjunctive therapy for the treatment of conditions associated with deficient circulation. Some examples include peripheral vascular disease, vascular spasm, migraine headache, Meniere's syndrome and vertigo.
Niacin has also been recommended for a variety of other conditions. Some examples include schizophrenia, chronic brain syndrome, acne, leg cramps and alcoholism.
The consumption of niacin is usually accompanied by facial and truncal flushing associated with warmth and tingling in these areas. These side effects usually occur in nearly all users shortly after ingestion of doses as small as 75 mg of niacin. Facial and truncal flushing are believed to be the result of peripheral vasodilation, predominantly of cutaneous vessels in the face, neck and chest. This niacin flush reaction is believed to be mediated by prostaglandins (e.g., prostacyclin), and is generally considered harmless.
Based on the foregoing, there is a need for a more effective treatment of chronic pain associated with muscle spasms, tendonitis and sciatica. Accordingly, it is one of the objects of the present invention to provide a superior treatment for chronic pain associated with muscle spasms, tendonitis and sciatica.